tests: fix/improve "TUI background color" tests (#10229)

- Ensure the opposite of the expected bg is active.
- Improves performance: 1.2s instead of 4.5s.

1 files changed, 74 insertions, 60 deletions

diff --git a/test/functional/terminal/tui_spec.lua b/test/functional/terminal/tui_spec.lua
index 0522d59c9a..9a907ade29 100644
--- a/test/functional/terminal/tui_spec.lua
+++ b/test/functional/terminal/tui_spec.lua
@@ -886,9 +886,9 @@ describe('TUI background color', function()
     screen:expect{any='did OptionSet, yay!'}
   end)
 
-  local function assert_bg(colorspace, color, bg)
-    it('handles '..color..' as '..bg, function()
-      feed_data('\027]11;'..colorspace..':'..color..'\007')
+  it("handles deferred background color", function()
+    local last_bg = 'dark'
+    local function wait_for_bg(bg)
       -- Retry until the terminal response is handled.
       retry(100, nil, function()
         feed_data(':echo &background\n')
@@ -905,62 +905,76 @@ describe('TUI background color', function()
           ]], bg)
         })
       end)
-    end)
-  end
+      last_bg = bg
+    end
+
+    local function assert_bg(colorspace, color, bg)
+      -- Ensure the opposite of the expected bg is active.
+      local other_bg = (bg == 'dark' and 'light' or 'dark')
+      if last_bg ~= other_bg then
+        feed_data(other_bg == 'light' and '\027]11;rgb:f/f/f\007'
+                                      or  '\027]11;rgb:0/0/0\007')
+        wait_for_bg(other_bg)
+      end
 
-  assert_bg('rgb', '0000/0000/0000', 'dark')
-  assert_bg('rgb', 'ffff/ffff/ffff', 'light')
-  assert_bg('rgb', '000/000/000', 'dark')
-  assert_bg('rgb', 'fff/fff/fff', 'light')
-  assert_bg('rgb', '00/00/00', 'dark')
-  assert_bg('rgb', 'ff/ff/ff', 'light')
-  assert_bg('rgb', '0/0/0', 'dark')
-  assert_bg('rgb', 'f/f/f', 'light')
-
-  assert_bg('rgb', 'f/0/0', 'dark')
-  assert_bg('rgb', '0/f/0', 'light')
-  assert_bg('rgb', '0/0/f', 'dark')
-
-  assert_bg('rgb', '1/1/1', 'dark')
-  assert_bg('rgb', '2/2/2', 'dark')
-  assert_bg('rgb', '3/3/3', 'dark')
-  assert_bg('rgb', '4/4/4', 'dark')
-  assert_bg('rgb', '5/5/5', 'dark')
-  assert_bg('rgb', '6/6/6', 'dark')
-  assert_bg('rgb', '7/7/7', 'dark')
-  assert_bg('rgb', '8/8/8', 'light')
-  assert_bg('rgb', '9/9/9', 'light')
-  assert_bg('rgb', 'a/a/a', 'light')
-  assert_bg('rgb', 'b/b/b', 'light')
-  assert_bg('rgb', 'c/c/c', 'light')
-  assert_bg('rgb', 'd/d/d', 'light')
-  assert_bg('rgb', 'e/e/e', 'light')
-
-  assert_bg('rgb', '0/e/0', 'light')
-  assert_bg('rgb', '0/d/0', 'light')
-  assert_bg('rgb', '0/c/0', 'dark')
-  assert_bg('rgb', '0/b/0', 'dark')
-
-  assert_bg('rgb', 'f/0/f', 'dark')
-  assert_bg('rgb', 'f/1/f', 'dark')
-  assert_bg('rgb', 'f/2/f', 'dark')
-  assert_bg('rgb', 'f/3/f', 'light')
-  assert_bg('rgb', 'f/4/f', 'light')
-
-  assert_bg('rgba', '0000/0000/0000/0000', 'dark')
-  assert_bg('rgba', '0000/0000/0000/ffff', 'dark')
-  assert_bg('rgba', 'ffff/ffff/ffff/0000', 'light')
-  assert_bg('rgba', 'ffff/ffff/ffff/ffff', 'light')
-  assert_bg('rgba', '000/000/000/000', 'dark')
-  assert_bg('rgba', '000/000/000/fff', 'dark')
-  assert_bg('rgba', 'fff/fff/fff/000', 'light')
-  assert_bg('rgba', 'fff/fff/fff/fff', 'light')
-  assert_bg('rgba', '00/00/00/00', 'dark')
-  assert_bg('rgba', '00/00/00/ff', 'dark')
-  assert_bg('rgba', 'ff/ff/ff/00', 'light')
-  assert_bg('rgba', 'ff/ff/ff/ff', 'light')
-  assert_bg('rgba', '0/0/0/0', 'dark')
-  assert_bg('rgba', '0/0/0/f', 'dark')
-  assert_bg('rgba', 'f/f/f/0', 'light')
-  assert_bg('rgba', 'f/f/f/f', 'light')
+      feed_data('\027]11;'..colorspace..':'..color..'\007')
+      wait_for_bg(bg)
+    end
+
+    assert_bg('rgb', '0000/0000/0000', 'dark')
+    assert_bg('rgb', 'ffff/ffff/ffff', 'light')
+    assert_bg('rgb', '000/000/000', 'dark')
+    assert_bg('rgb', 'fff/fff/fff', 'light')
+    assert_bg('rgb', '00/00/00', 'dark')
+    assert_bg('rgb', 'ff/ff/ff', 'light')
+    assert_bg('rgb', '0/0/0', 'dark')
+    assert_bg('rgb', 'f/f/f', 'light')
+
+    assert_bg('rgb', 'f/0/0', 'dark')
+    assert_bg('rgb', '0/f/0', 'light')
+    assert_bg('rgb', '0/0/f', 'dark')
+
+    assert_bg('rgb', '1/1/1', 'dark')
+    assert_bg('rgb', '2/2/2', 'dark')
+    assert_bg('rgb', '3/3/3', 'dark')
+    assert_bg('rgb', '4/4/4', 'dark')
+    assert_bg('rgb', '5/5/5', 'dark')
+    assert_bg('rgb', '6/6/6', 'dark')
+    assert_bg('rgb', '7/7/7', 'dark')
+    assert_bg('rgb', '8/8/8', 'light')
+    assert_bg('rgb', '9/9/9', 'light')
+    assert_bg('rgb', 'a/a/a', 'light')
+    assert_bg('rgb', 'b/b/b', 'light')
+    assert_bg('rgb', 'c/c/c', 'light')
+    assert_bg('rgb', 'd/d/d', 'light')
+    assert_bg('rgb', 'e/e/e', 'light')
+
+    assert_bg('rgb', '0/e/0', 'light')
+    assert_bg('rgb', '0/d/0', 'light')
+    assert_bg('rgb', '0/c/0', 'dark')
+    assert_bg('rgb', '0/b/0', 'dark')
+
+    assert_bg('rgb', 'f/0/f', 'dark')
+    assert_bg('rgb', 'f/1/f', 'dark')
+    assert_bg('rgb', 'f/2/f', 'dark')
+    assert_bg('rgb', 'f/3/f', 'light')
+    assert_bg('rgb', 'f/4/f', 'light')
+
+    assert_bg('rgba', '0000/0000/0000/0000', 'dark')
+    assert_bg('rgba', '0000/0000/0000/ffff', 'dark')
+    assert_bg('rgba', 'ffff/ffff/ffff/0000', 'light')
+    assert_bg('rgba', 'ffff/ffff/ffff/ffff', 'light')
+    assert_bg('rgba', '000/000/000/000', 'dark')
+    assert_bg('rgba', '000/000/000/fff', 'dark')
+    assert_bg('rgba', 'fff/fff/fff/000', 'light')
+    assert_bg('rgba', 'fff/fff/fff/fff', 'light')
+    assert_bg('rgba', '00/00/00/00', 'dark')
+    assert_bg('rgba', '00/00/00/ff', 'dark')
+    assert_bg('rgba', 'ff/ff/ff/00', 'light')
+    assert_bg('rgba', 'ff/ff/ff/ff', 'light')
+    assert_bg('rgba', '0/0/0/0', 'dark')
+    assert_bg('rgba', '0/0/0/f', 'dark')
+    assert_bg('rgba', 'f/f/f/0', 'light')
+    assert_bg('rgba', 'f/f/f/f', 'light')
+  end)
 end)